Trifluoroethylene, CF2═CHF or R1123, and 1,1,1,2-tetrafluoropropene, CF3—CF═CH2 or R1234yf, are very useful, high-priced, high-demand monomers for the preparation of fluorocarbon polymers. The need for trifluoroethylene and tetrafluoropropylene as a monomer for producing fluorocarbon polymers has enormous growth potential as the need for fluorocarbon polymers is expected to grow rapidly.
There is, however, no cost effective and simple way to produce trifluoroethylene (R1123) and tetrafluoropropylene (R1234yf). Trifluoroethylene can be produced from CCl2FCClF2 (R113) by reaction with hydrogen in the presence of a catalyst comprising palladium and at least one other metal selected from gold, tellurium, antimony, bismuth and arsenic as disclosed in U.S. Pat. No. 5,283,379. Trifluoroethylene can also be prepared from CF2═CClF (R1113) by reaction with hydrogen in the presence of a catalyst comprising palladium or platinum on a magnesium oxide carrier as disclosed in U.S. Pat. No. 5,089,454. In U.S. Pat. No. 5,892,135 it is disclosed that trifluoroethylene is prepared. in high yield and selectivity by contacting, in the vapor phase, at least one halogenated ethane CF3CClFX where X═H, Cl or F, e.g., 2,2-dichloro-1,1,1,2-tetrafluoroethane, by reaction with hydrogen in the presence of a catalyst comprising at least one component selected from metals, metal oxides, metal halides, and metal oxyhalides of ruthenium, copper, nickel, and/or chromium and the halogen of the halides and the oxyhalides is fluorine and/or chlorine. European Patent Publication No. 0 747 337 A1 disclosed a process for the preparation of chlorotrifluoroethylene and trifluoroethylene by the reaction of 1,1,2-trichloro-1,2,2-trifluoroethane with hydrogen in the presence of a catalyst system comprising 12–22% of Cu as well as a Group VIIIB element on a carbon support. WO 9729065 A1 discloses a process in which a gaseous feed of steam and a saturated hydrohalocarbon having a fluorine substituent and one or more further halogen substituents, e.g., 1,1,1,2-tetrafluoroethane, is passed through a heated reaction zone and the fluorinated alkene, e.g., trifluoroethylene, is recovered. French Patent 2,729,136 discloses a process, which enables the doping of the catalyst for stability. A stream of fluoroalkane containing BF3 and, optionally N, is passed continuously over an AIF3 catalyst at 400–600° C. Passing a mixture. of CF3CH2F 59.8, N 59.9, and BF3 15.8 mmol/h over an AIF3 catalyst at 470° C./1 atmosphere and 65 h gave a conversion of CF3CH2F of 12.8 and 13.7%, and selectivity for CF2:CHF of 94.5 and 98.5%, respectively; vs. 14.2%, 7.7%, 95.8%, and 97.4%, respectively., after 15 and 63 h in the absence of BF3. In Japanese Patent No. JP 43-008454 trifluoroethylene is prepared. by a 1-step reaction of CCl2FCClF2 and hydrogen over a Pd or Pt catalyst at 200–300° C. A 1:2 molar CCl2FCClF2:hydrogen feed was passed through a quartz tube (20×700 mm.) containing 5% Pd—C with a space velocity of 144 L./l hr to give the following results: reaction temp., % CCl2FCClF2 conversion, and mole % trifluoroethylene in the product given—: 200° C., 60.0%, 65.3%; 250° C., 69.4%, 56.4&; 300° C., 86.5%, 30.8%, together with 39.2 mole % CClF2CHClF. In Journal of Electroanalytical Chemistry (1997), 435 (1–2), 255–258 there is disclosed that chlorotrifluoroethene was the unique product described in the literature from the electroredeposition of 1,1,2-trichloro-1,2,2-trifluoroethane (R 113). Preliminary results on new electrosynthetic possibilities of the electroredeposition. of R 113 on Pb and Cd cathodes in MeOH—H2O solutions. containing. ammonium salts and different cations are reported. The essential result was that trifluoroethene, difluoroethene, difluoroethane and fluoroethane were produced instead of chlorotrifluoroethene when Pd2+ salts were added into the electrolyte. The use of a hydrogen diffusion anode permitted conducting the electrosynthesis in a monocompartimental cell without undesirable by-products. Japanese Patent publication JP 2002275106 relates to a Process for producing fluorinated aliphatic compounds by pyrolysis of perfluorocarboxylic acids and their halides and esters. The pyrolysis is carried out in the presence of a catalyst comprising a carrier most preferably chosen among active carbon, MgO, CaO, BaO, ZnO, Al2O3, NiO, and SiO2 promoted with alkali metal halides selected from the series comprising fluorides, chlorides, bromides, iodides of sodium, potassium, rubidium, cesium at approximately. 100–450° C. to prepare fluorinated aliphatic compounds comprising perfluoroolefins, polyfluoroolefins and their derivatives, and optionally, in the presence of additional HF to form fluorinated aliphatic compounds comprising polyfluoroalkanes and their derivatives. Thus, pyrolysis of perfluorovaleric acid Me ester using SiO2/KF as catalyst at 240° C. gave 95.1% perfluoro-2-butene.
Russian Patent RU 218814 Cl relates to a Thermal decomposition process for the integrated production of perfluorocarbons. The production. of industrially important fluorocarbons, in particular tetrafluoroethylene, hexafluoropropylene, and octafluorocyclobutane, is accomplished via the thermal decomposition of difluorochloromethane with steam and tetrafluorochloroethane. The pyrolyzate is subjected to tempering, freed of HCl (for the production. of hydrochloric acid), neutralized, compressed, and condensed in a three-step process receiving a polymerization inhibitor before the first and second condensation steps. From the second-step condensate, low-boiling substances are removed by rectification and tetrafluoroethylene is recovered. The bottoms fraction is combined with the first-step condensate and the resulting mixture is subjected to a multi-step rectification to yield fractions of difluorochloromethane/hexafluoropropylene and tetrafluorochloroethane/octafluorocyclobutane azeotropes, from which hexafluoropropylene and oectafluorocyclobutane are isolated. In the third condensation step, difluorochloromethane or indicated azeotropes are additionally. introduced. The third-step condensate is added to still fraction-first-step condensate mixture and, from the combined mixture before isolation of above-indicated azeotropes, the first tetrafluoroethylene-containing gases (which are transferred into the pyrolyzate compression stage) and then, optionally, trifluoroethylene are rectified into a light-boiling fraction. The tetrafluoroethylene concentration in the third-step condensate is maintained at 10–30%. In Chinese patent No. 1351903 hydrodechlorination catalysts for preparing trifluorochloroethylene and trifluoroethylene is composed of Ru (or Pd and Pt) and Cu as active compounds.; lanthanide-rich rare earth metal mixtures (or La) and lithium as modifiers; and coconut shell activated carbon as support. In WO 2004 080937 there is disclosed a process for manufacture of fluorinated monomers. The process is disclosed for the conversion of fluorocarbons into fluorinated unsaturated compounds useful as monomers or other chemical precursors, such as C2H2F2. The process comprises reacting a hydrocarbon feed and a fluorocarbon feed in a high temperature reactor at a sufficiently high temperature and sufficiently short resident time to form a reaction product mixture having the fluorinated unsaturated compound as the major reaction product, and cooling it to a temperature sufficiently low to inhibit polymerization of the unsaturated compound. The reaction product may then be processed by removal of higher molecular weight compounds and acids and optionally separated into product components.
Despite these processes, there is a need for a relatively inexpensive and simple process for the production of trifluoroethylene and tetrafluoropropylene, and particularly one that does not require the use of hydrogen gas and is thereby enabled to avoid the major concern with safety related issues associated with the handling of hydrogen gas in large scale production.